A multi-disc magnetic storage device is configured to perform recording/retrieving of information with respect to plural magnetic discs which are storage media by plural sets of magnetic heads. One multi-disc magnetic storage device includes a head stack assembly having plural actuator arms to which plural magnetic heads for the surface, and plural magnetic heads for the back, are respectively attached which are incorporated to discs as plural storage media according to the storage capacity (the number of discs).
In the head stack assembly to which plural magnetic heads are assembled, plural magnetic heads for the surface and plural magnetic heads for the back are provided alternately with respect to plural discs which are storage media. The magnetic head for the surface and the magnetic head for the back are designed and manufactured so that an air-bearing surface and the like is almost line-symmetrical with respect to a disc for realizing highly accurate low flying. That is, the magnetic head for the surface and the magnetic head for the back are formed in accordance with different design drawings.
Here, the magnetic heads, particularly, read elements and write elements in the magnetic head are manufactured with microfabrication, and the completed read elements and write elements of the magnetic head may vary in quality. Both the magnetic heads for the surface and the magnetic heads for the back are randomly assembled to the head stack assembly when they are within a certain degree of tolerance.
Additionally, it is known that variation of the magnetic core width of the magnetic head particularly affects quality of the multi-disc magnetic storage device. For example, in U.S. Pat. No. 7,023,633 (“Patent Document 1”), magnetic heads to be assembled to the head stack assembly may be finely classified into similar core widths in advance in accordance with the core width and that the magnetic heads having the similar core width are assembled to the same head stack assembly.
As described above, in the method in which both the magnetic heads for the surface and the magnetic heads for the back are randomly assembled to the head stack assembly when they are within a certain degree of tolerance, when the good product rates (yield as the multi-disc magnetic storage devices) is intended to be increased, the tolerance has to be narrowed. As a result, the yield of the magnetic head may be low, which increases manufacturing costs.
Also in the method described in Patent Document 1, it may be necessary to align magnetic heads having similar core widths. Actually, it is difficult to align magnetic heads having similar core widths unless a large number of magnetic heads are manufactured. As a result, inventory of the manufactured magnetic heads continues to increase, which increases manufacturing costs as the multi-disc magnetic storage device.